There is the likelihood in bending machines for bending rod-shaped or tubular workpieces by means of the bending head that the continuously fed workpiece to be processed is subjected to highly undesirable warpage (kinks, bulges, etc.) by the forces occurring during the bending in a certain region before its entrance into the forming groove of the bending form during the bending process in which it is bent in a circular manner, or in the manner of the segment of a circle, by means of a bending disk comprising a forming groove in which the workpiece is disposed, and an associated bending finger.
In order to prevent this, support jaws are placed in known bending machines in the mentioned region against the same on the side of the workpiece to be treated which is averted from the bending head and the bending disk.
DE 201 18444 U1 shows such an arrangement, with a support jaw being provided there which can be displaced along the tubular body and perpendicular to the same. This known support jaw arrangement can only be used in the case of a one-sided bending of the tubular workpiece because it allows support against bending forces on only one side.
In the support jaw arrangement from U.S. Pat. No. 4,959,984, a lateral support jaw is used which can be displaced perpendicularly to the longitudinal axis of the workpiece to be treated from an engagement position to a removed non-engagement position. Bending of this workpiece is also only possible on one side.
The same arrangement is principally also shown by DE 601 00 147 T2 and EP 0 934 783 B1 and DE 3922326 C2.
An apparatus is known from WO 2004/000479 A1 with which the workpiece to be processed can be bent to the right and left. A support jaw is placed in this case too in the region before the tangential entrance of the rod-shaped or tubular workpiece into the forming groove of the bending disk, with two such support jaws being provided here, one each for a bending direction, with each of which having a forming groove for placement against one side of the workpiece. The forming grooves on both support jaws as well as those on the bending disk are arranged in different axial height. In order to change over from right to left bending, complex rotation and pivoting motions and displacement motions along a clamping table are required in this known apparatus in order to displace the tool to the respectively opposite side of the bending head into the other forming groove of the same in the case of a fixed bending head and thus to also place the support jaws and the clamping devices on the other side of the bending head, by means of which the workpiece is guided during bending about the bending form. The constructional effort is considerable and the arrangement is very complex. As a result of the large overall size, the available bending space is restricted considerably to the side.
A further pipe bending machine is finally known from EP 0 649 687 B1 with which bending to the right and left is possible. Two support jaws are used in this case too, which are attached to opposite sides of the bending head and are each displaceable in the direction towards the workpiece to be processed until resting against the same. During the bending process, the respective support jaw which is in use will automatically follow the continuously conveyed tubular workpiece. The bending head is provided with a laterally protruding swivel arm to which two further clamping jaws which can be displaced individually on the bending head are attached for clamping the tube against a clamping element attached to the bending head, which clamping jaws produce the bending process after the clamping by pivoting the swivel arm about the swiveling axis of the bending head. When a changeover from one bending direction to another is desired, the swivel arm needs to be brought for this purpose to a pivoting position which is twisted by 180°, so that it can cooperate on the opposite side of the bending head with the other support jaw which is present there. This known bending machine is also complex in its configuration, with the support jaws having to be moved both in the longitudinal direction of the workpiece to be processed as well as perpendicular to its longitudinal axis. Furthermore, the forming grooves in the two forming jaws and the respectively associated forming grooves in the bending disk are disposed at different heights, also leading to a change of the height position of the overall arrangement relative to the fed strand-like workpiece during the changeover of the bending direction.